Example embodiments relate to a method of fabricating an image sensor. Example embodiments also relate to a method of fabricating a complementary metal-oxide-semiconductor (CMOS) image sensor having an inner lens. An image sensor may convert an optical image into an electrical signal. With the development of the computer and communication industries, the demand for an improved image sensor has been increasing in various fields, e.g., digital cameras, camcorders, personal communication systems (PCS), game machines, surveillance cameras, and/or medical microcameras.
CMOS image sensors may be easier to operate and may be realized using various scanning methods. Also, CMOS image sensors may be beneficial with regard to the fabrication of smaller-sized products by allowing signal processing circuits to be integrated onto a single chip, thus reducing fabrication costs. In addition, because CMOS image sensors may require lower power consumption, they may be beneficial to products having lower battery capacity. As a result, the use of CMOS image sensors has been increasing with the realization of megapixel resolution. However, as the pixel integration degree increases (e.g., from about 1 M to about 2 M and/or 5 M), photodiode area per unit pixel may decrease. To increase the concentration of light onto the decreased photodiode area, research regarding the use of an inner lens has been actively conducted.
An inner lens may further concentrate light that has already been concentrated by a microlens such that oblique light may be reduced and more light may reach a photodiode. A conventional method may require additional processes for forming an inner lens. These additional processes may complicate the overall manufacturing process, thus increasing fabrication costs. Conventionally, an inner lens molding layer may need to be deposited and patterned to form an inner lens mold prior to actually forming the inner lens in the mold. For example, a copper interconnection may provide improved performance (compared to an aluminum interconnection, for instance) when used in an image sensor, but the fabrication process may also be more complicated. Accordingly, the additional processes used in a conventional method for forming an inner lens may not be desirable because of increased fabrication costs.